Background: Military samples provide an excellent context to systematically ascertain hospitalization for severe psychiatric disorders. The National Collaborative Study of Early Psychosis and Suicide (NCSEPS), a collaborative study of psychiatric disorders in the US Armed Forces, estimated rates of first hospitalization in the military for three psychiatric disorders: bipolar disorder (BD), major depressive disorder (MDD) and schizophrenia.
Method: First hospitalizations for BD, MDD and schizophrenia were ascertained from military records for active duty personnel between 1992 and 1996. Rates were estimated as dynamic incidence (using all military personnel on active duty at the midpoint of each year as the denominator) and cohort incidence (using all military personnel aged 18-25 entering active duty between 1992 and 1996 to estimate person-years at risk).
Results: For all three disorders, 8723 hospitalizations were observed in 8,120,136 person-years for a rate of 10.7/10,000 [95% confidence interval (CI) 10.5-11.0]. The rate for BD was 2.0 (95% CI 1.9-2.1), for MDD, 7.2 (95% CI 7.0-7.3), and for schizophrenia, 1.6 (95% CI 1.5-1.7). Rates for BD and MDD were greater in females than in males [for BD, rate ratio (RR) 2.0, 95% CI 1.7-2.2; for MDD, RR 2.9, 95% CI 2.7-3.1], but no sex difference was found for schizophrenia. Blacks had lower rates than whites of BD (RR 0.8, 95% CI 0.7-0.9) and MDD (RR 0.8, 95% CI 0.8-0.9), but a higher rate of schizophrenia (RR 1.5, 95% CI 1.3-1.7).
Conclusions: This study underscores the human and financial burden that psychiatric disorders place on the US Armed Forces.